Expanded spectrum of varicella disease and the need for vaccination in India

Varicella vaccine was first licensed in Japan and South Korea in 1989 for use in healthy children and was introduced in US in 1995. So far, 29 countries have adopted varicella vaccine in their universal immunization program (UIP). No Asian country, India included, has adopted the varicella vaccine as part of their UIP. The extra-cutaneous sites for VZV diseases are central nervous system and gastrointestinal tract, the expanded disease spectrum includes vasculopathy, myelitis, inflammatory bowel disease, perforated ulcers, and gastritis. The actual disease burden of varicella is not known as most of the infected individuals may not visit the physician. The amplifiable VZV DNA will not always be detectable in cerebrospinal fluid (CSF) samples in protracted illnesses such as vasculopathies, but demonstrable anti-VZV IgG in CSF has diagnostic value. The World Health Organization (WHO) position paper 2014 recommends two doses of varicella and zoster vaccines in targeted population. In India, varicella vaccine is not included in the UIP due to the cost and the belief that lifelong immunity occurs following primary infection. The expanded spectrum of VZV disease and the mounting body of evidence, however, suggest the need for both varicella and zoster vaccines in routine immunization schedule.

A data-driven reduced-order surrogate model for entire elastoplastic simulations applied to representative volume elements

This contribution discusses surrogate models that emulate the solution field(s) in the entire simulation domain. The surrogate uses the most characteristic modes of the solution field(s), in combination with neural networks to emulate the coefficients of each mode. This type of surrogate is well known to rapidly emulate flow simulations, but rather new for simulations of elastoplastic solids. The surrogate avoids the iterative process of constructing and solving the linearized governing equations of rate-independent elastoplasticity, as necessary for direct numerical simulations or (hyper-)reduced-order-models. Instead, the new plastic variables are computed only once per increment, resulting in substantial time savings. The surrogate uses a recurrent neural network to treat the path dependency of rate-independent elastoplasticity within the neural network itself. Because only a few of these surrogates have been developed for elastoplastic simulations, their potential and limitations are not yet well studied. The aim of this contribution is to shed more light on their numerical capabilities in the context of elastoplasticity. Although more widely applicable, the investigation focuses on a representative volume element, because these surrogates have the ability to both emulate the macroscale stress-deformation relation (which drives the multiscale simulation), as well as to recover all microstructural quantities within each representative volume element.

Isoform-specific GSK3A activity is negatively correlated with human sperm motility

In mouse and bovine sperm, GSK3 activity is inversely proportional to motility. Targeted disruption of the GSK3A gene in testis results in normal spermatogenesis, but mature sperm present a reduced motility, rendering male mice infertile. On the other hand, GSK3B testis-specific KO is fertile. Yet in human sperm, an isoform-specific correlation between GSK3A and sperm motility was never established. In order to analyze GSK3 function in human sperm motility, normospermic and asthenozoospermic samples from adult males were used to correlate GSK3 expression and activity levels with human sperm motility profiles. Moreover, testicular and sperm GSK3 interactomes were identified using a yeast two-hybrid screen and coimmunoprecipitation, respectively. An extensive in-silico analysis of the GSK3 interactome was performed. The results proved that inhibited GSK3A (serine phosphorylated) presents a significant strong positive correlation (r = 0.822, P = 0.023) with the percentage of progressive human sperm, whereas inhibited GSK3B is not significantly correlated with sperm motility (r = 0.577, P = 0.175). The importance of GSK3 in human sperm motility was further reinforced by in-silico analysis of the GSK3 interactome, which revealed a high level of involvement of GSK3 interactors in sperm motility-related functions. The limitation of techniques used for GSK3 interactome identification can be a drawback, since none completely mimics the physiological environment. Our findings prove that human sperm motility relies on isoform-specific functions of GSK3A within this cell. Given the reported relevance of GSK3 protein-protein interactions in sperm motility, we hypothesized that they stand as potential targets for male contraceptive strategies based on sperm motility modulation.

Hepatitis B virus X protein: The X factor in chronic hepatitis B virus disease progression

Introduction

Hepatitis B virus (HBV) is the most common aetiological factor causing hepatocellular carcinoma (HCC). HBx gene plays an enigmatic role in HBV-related HCC. In this study we have analysed amino acid substitutions in HBx from HBV-infected individuals of different clinical stages.

Materials and Methods

HBV-infected individuals (n = 93) were recruited in the study. DNA was extracted from plasma, amplified, and DNA sequencing was performed using specific primers targeting HBx gene (540 bp).

Results

Among the study participants, 57% had chronic HBV infection, 30% had chronic liver disease (CLD) and 13% had HBV related HCC. Genotypes such as D1, D2, D3, A1, C2 and B2 were identified of which genotype D2 was predominant (78%). HBxC-terminal deletion was observed in four hepatitis B e antigen (HBeAg) negative participants with CLD. The frequency of aminoacid substitution in proapoptotic domain was higher in HBeAg negative participants including I127V (34%), K130M (34%), V131I (40%). The frequency of double mutation (K130M+V131I) and triple mutation (I127V+K130M+V131I) were found to be higher (32% and 36%) in HBeAg negative participants. Also, we identified L5M substitution (4.3%) in HBeAg positive participants with advanced liver disease.

Conclusion

In HBx gene, aminoacid substitutions at positions 127, 130, 131 are associated with poor expression of HBeAg. We suggest screening for HBx aminoacid substitutions especially in patients with HBeAg negative chronic HBV infection to predict the clinical outcome and enable early treatment to prevent disease progression.

Evaluation of impact of anti-idursulfase antibodies during long-term idursulfase enzyme replacement therapy in mucopolysaccharidosis II patients

OBJECTIVES

This 109-week, nonrandomized, observational study of mucopolysaccharidosis II (MPS II) patients already enrolled in the Hunter Outcome Survey (HOS) (NCT00882921), assessed the long-term immunogenicity of idursulfase, and examined the effect of idursulfase-specific antibody generation on treatment safety (via infusion-related adverse events [IRAEs]) and pharmacodynamics (via urinary glycosaminoglycans [uGAGs]).

METHODS

Male patients ≥ 5 years, enrolled in HOS regardless of idursulfase treatment status were eligible. Blood/urine samples for anti-idursulfase antibody testing and uGAG measurement were collected every 12 weeks.

RESULTS

Due to difficulties in enrolling treatment-naïve patients, data collection was limited to 26 enrolled patients of 100 planned patients (aged 5.1-35.5 years) all of whom were non-naïve to treatment. Fifteen (58%) patients completed the study. There were 11/26 (42%) seropositive patients at baseline (Ab +), and 2/26 (8%) others developed intermittent seropositivity by Week 13. A total of 9/26 patients (35%) had ≥ 1 sample positive for neutralizing antibodies. Baseline uGAG levels were low due to prior idursulfase treatment and did not change appreciably thereafter. Ab + patients had persistently higher uGAG levels at entry and throughout the study than Ab - patients. Nine of 26 (34%) patients reported IRAEs. Ab + patients appeared to have a higher risk of developing IRAEs than Ab - patients. However, the relative risk was not statistically significant and decreased after adjustment for age.

CONCLUSIONS

50% of study patients developed idursulfase antibodies. Notably Ab + patients had persistently higher average uGAG levels. A clear association between IRAEs and antibodies was not established.

Abstract P5-04-03: Palbociclib synergizes with autophagy inhibitors to induce senescence in breast cancer

This abstract was withdrawn by the authors.

Non-cirrhotic thrombocytopenic patients with hepatitis C virus: Characteristics and outcome of antiviral therapy

BACKGROUND AND AIM

Thrombocytopenia is frequently observed in patients with chronic hepatitis C virus (HCV) infection and cirrhosis, although it can also be observed in patients without cirrhosis by a virus-mediated phenomenon. This study assessed the prevalence, characteristics, and outcomes of antiviral therapy in patients with chronic HCV infection and thrombocytopenia not associated with cirrhosis.

METHODS

The study included 1268 patients with HCV infection and thrombocytopenia enrolled in the phase 3 ENABLE studies that assessed the impact of eltrombopag on achieving a sustained virologic response to pegylated interferon and ribavirin. The study population was subdivided according to baseline FibroSURE test results into patients with non-cirrhosis (FibroSURE < 0.4) and cirrhosis-related (FibroSURE ≥ 0.75) thrombocytopenia.

RESULTS

Compared with patients with cirrhosis-related thrombocytopenia (n = 995; 78.5%), non-cirrhotic patients with thrombocytopenia (n = 59; 4.6%) were younger (mean age [95% confidence interval (CI)]: 43.9 [40.7-47.2] vs 52.7 [52.2-53.3] years; P < 0.0001), predominantly female (64% [51-76] vs 30% [27-33]; P < 0.0001), and less frequently had a Model for End-Stage Liver Disease score ≥ 10 (24% [14-37] vs 45% [42-49]; P = 0.0012), low albumin levels (≤ 35 g/L; 2% [0-9] vs 32% [29-35]; P < 0.0001), and prevalence of diabetes mellitus (3% [0-12] vs 21% [19-24]; P = 0.0005). The sustained virologic response rate was higher in non-cirrhotic patients with thrombocytopenia (46% [95% CI, 33-59] vs 16% [14-18]; P < 0.0001).

CONCLUSIONS

Patients with thrombocytopenia associated with HCV who have lower FibroSURE test results may have better preserved liver function and higher sustained virologic response rates than patients with cirrhosis.

Nicotinic receptors containing the alpha7 subunit: a model for rational drug design

The neuronal nicotinic receptor has gained considerable recognition as a target, not just for combating drug addiction but also for treating a number of illnesses ranging from neurodegenerative diseases to psychotic disorders like schizophrenia. This recognition has led to a burgeoning field examining the receptor at all levels. A class of nicotinic receptors that contains the alpha7 gene product, apparently as a homomer, illustrates this multidisciplinary approach. Here, we review recent progress in our understanding of this class of receptors based on data from molecular, structural, physiological and patho-physiological studies. These studies have set the stage for rational drug design to combat disorders of the central nervous system. The studies also exemplify the cautious approach needed in developing CNS therapies and the importance of physiology in tempering drug design.

Rare finding of a gastrojejuno appendicular fistula during a laparotomy for roux-en-y conversion

Gastrojejuno appendicular fistula is a rare condition. To our knowledge it has not been reported previously in the literature. We report the first case of a gastrojejuno appendicular fistula occurring in a patient who had previous gastroenterostomy for ulcer disease. He presented to us with recurrent episodes of abdominal pain and bilious vomiting. An endoscopy revealed intense gastritis with bile reflux. He was diagnosed as alkaline gastritis and put on medication. As there was no relief of his symptoms; it was decided to do a biliary diversion. At laparotomy there were extensive adhesions which was gently separated. Patient had an anticolic anastomosis and a long tubular structure was seen fistulating to the stoma site. It was traced and found to be the appendix. The gastrojejunal stoma was opened and the fistulous mouth was identified and cannulated following, which a retrograde appendicectomy was performed and a cuff of intestine around the fistula was excised. The Stoma was closed in a single layer. A Braun's enteroenterostomy was done to correct the alkaline reflux. The patient is symptomatically better and is gaining weight. The pathogenesis of alkaline gastritis. appendicular fistula and gastrojejunocolic fistula is discussed.

Reproductive function for a C-terminus extended, male-transmitted cytochrome c oxidase subunit II protein expressed in both spermatozoa and eggs

Our previous study documented expression of a male-transmitted cytochrome c oxidase subunit II protein (MCOX2), with a C-terminus extension (MCOX2e), in unionoidean bivalve testes and sperm mitochondria. Here, we present evidence demonstrating that MCOX2 is seasonally expressed in testis, with a peak shortly before fertilization that is independent of sperm density. MCOX2 is localized to the inner and outer sperm mitochondrial membranes and the MCOX2 antibody's epitope is conserved across >65 million years of evolution. We also demonstrate the presence of male-transmitted mtDNA and season-specific MCOX2 spatial variation in ovaries. We hypothesize that MCOX2 plays a role in reproduction through gamete maturation, fertilization and/or embryogenesis.

The molecular basis of "curlicue": a sperm motility abnormality linked to the sterility of t haplotype homozygous male mice

The t complex, a variant region of chromatin occupying approximately 40-million base pairs of proximal chromosome 17, exists in natural populations of wild mice of the Mus musculus species as a family of homologues called t haplotypes (t). Relative to wild-type (+) homologues, all t haplotypes share four large non-overlapping inversions, spanning 95% of the region, leading to intra-inversion recombination suppression in +/t heterozygotes. Non-lethal t homozygous males or complementing recessive lethal t doubly heterozygous males (hereafter both abbreviated "t/t males") are invariably and completely sterile, due to expression of several sperm function abnormalities. One of these traits, "curlicue", describes a condition in which spermatozoa from t/t males fail to reach the site of fertilization in vivo because they exhibit a severe loss of vigorous forward motility due to the chronic negative curvature of their flagella. Current data indicate that "curlicue" is the complex phenotypic reflection of the expression of three or more mutations clustered in the distal one-third of the largest and most-distal t complex inversion, In(17)4. From proximal to distal, candidates include Dnahc8, Tsga2 and Tctex5. Interestingly, new results from high-resolution intra-inversion genetic mapping and protein localization studies suggest that the products of the distal two candidates, Tsga2 and Tctex5, might play synergic roles in the expression of both the "curlicue" motility abnormality and the "stop" sperm-egg interaction aberration, regarded as functionally unrelated traits.

Recombinant human acid [alpha]-glucosidase: major clinical benefits in infantile-onset Pompe disease

BACKGROUND

Pompe disease is a progressive metabolic neuromuscular disorder resulting from deficiency of lysosomal acid alpha-glucosidase (GAA). Infantile-onset Pompe disease is characterized by cardiomyopathy, respiratory and skeletal muscle weakness, and early death. The safety and efficacy of recombinant human (rh) GAA were evaluated in 18 patients with rapidly progressing infantile-onset Pompe disease.

METHODS

Patients were diagnosed at 6 months of age and younger and exhibited severe GAA deficiency and cardiomyopathy. Patients received IV infusions of rhGAA at 20 mg/kg (n = 9) or 40 mg/kg (n = 9) every other week. Analyses were performed 52 weeks after the last patient was randomized to treatment.

RESULTS

All patients (100%) survived to 18 months of age. A Cox proportional hazards analysis demonstrated that treatment reduced the risk of death by 99%, reduced the risk of death or invasive ventilation by 92%, and reduced the risk of death or any type of ventilation by 88%, as compared to an untreated historical control group. There was no clear advantage of the 40-mg/kg dose with regard to efficacy. Eleven of the 18 patients experienced 164 infusion-associated reactions; all were mild or moderate in intensity.

CONCLUSIONS

Recombinant human acid alpha-glucosidase is safe and effective for treatment of infantile-onset Pompe disease. Eleven patients experienced adverse events related to treatment, but none discontinued. The young age at which these patients initiated therapy may have contributed to their improved response compared to previous trials with recombinant human acid alpha-glucosidase in which patients were older.

Presence of a unique male-specific extension of C-terminus to the cytochrome c oxidase subunit II protein coded by the male-transmitted mitochondrial genome of Venustaconcha ellipsiformis (Bivalvia: Unionoidea)

Analyses of unionoidean bivalve male-transmitted (M) mtDNA genomes revealed an approximately 555 bp 3' coding extension to cox2. An antibody was generated against this predicted C-terminus extension to determine if the unique cox2 protein is expressed. Western blot and immunohistochemistry analyses demonstrated that the protein was predominantly expressed in testes. Weak expression was detected in other male tissues but the protein was not detected in female tissues. This is the first report documenting the expression of a cox2 protein with a long C-terminus in animals. Its universal presence in unionoidean bivalve testes suggests a functional significance for the protein.

Carbofuran toxicity on total lipids and free fatty acids in air breathing fish during exposure and cessation of exposure--in vivo

Clarias batrachus, fish were exposed to sublethal concentration of commercial carbofuran for 144 hr. After 144 hr of exposure period, fish were transferred to fresh water and kept in the same for 144 hr in order to study the effect of carbofuran after cessation of intoxication. Total lipids and free fatty acids were determined in liver, muscle kidney and ovary at an interval of 24, 72 and 144 hr during exposure and after the release into toxicant free water. Total lipids increased in all the tissues throughout the exposure period, followed by decrease during depuration period. The results showed an alteration in free fatty acid content in different tissues of the fish. The elevated levels returned to almost control values after transfer of fish into carbofuran free water.

Nicotinic cholinergic signaling in hippocampal astrocytes involves calcium-induced calcium release from intracellular stores

In this report we provide evidence that neuronal nicotinic acetylcholine receptors (nAChRs) are present on hippocampal astrocytes and their activation produces rapid currents and calcium transients. Our data indicate that these responses obtained from astrocytes are primarily mediated by an AChR subtype that is functionally blocked by alpha-bungarotoxin (alpha Bgt) and contains the alpha7 subunit (alpha Bgt-AChRs). Furthermore, their action is unusual in that they effectively increase intracellular free calcium concentrations by activating calcium-induced calcium release from intracellular stores, triggered by influx through the receptor channels. These results reveal a mechanism by which alpha Bgt-AChRs on astrocytes can efficiently modulate calcium signaling in the central nervous system in a manner distinct from that observed with these receptors on neurons.

Optical measurements of presynaptic nicotinic effects

We have used the styryl dye FM 2-10 to monitor changes in synaptic activity mediated by nicotinic acetylcholine receptors (AChRs) on cultured hippocampal neurons. We show that both 100 microM ACh and nicotine at 20 microM causes a significant increase in staining intensities of presynaptic boutons in the presence of 0.5 microM tetrodotoxin (TTX). This effect of nicotine is blocked by d-tubocurarine. Interestingly, nicotine also had a long-lasting effect on high potassium-induced staining of boutons. These results suggest that nicotine can have significant and sustained effects on synaptic efficacy in cultured hippocampal neurons.

A role for phosphorylation of glycogen synthase kinase-3alpha in bovine sperm motility regulation

The long-term goal of our work is to understand biochemical mechanisms underlying sperm motility and fertility. In a recent study we showed that tyrosine phosphorylation of a 55-kDa protein varied in direct proportion to motility. Tyrosine phosphorylation of the protein was low in immotile compared to motile epididymal sperm. Inhibition or stimulation of motility by high calcium levels or cAMP, respectively, results in a corresponding decrease or increase in tyrosine phosphorylation of the 55-kDa protein. Here we report purification and identification of this motility-associated protein. Soluble extracts from bovine caudal epididymal sperm were subjected to DEAE-cellulose, Affi-Gel blue, and cellulose phosphate chromatography. Tyrosine phosphate immunoreactive fractions contained glycogen synthase kinase-3 (GSK-3) activity, suggesting a possible correspondence between these proteins. This suggestion was verified by Western blot analyses following one-dimensional and two-dimensional gel electrophoresis of the purified protein using monoclonal and affinity-purified polyclonal antibodies against the catalytic amino-terminus and carboxy-terminus regions of GSK-3. Further confirmation of the identity of these proteins came from Western blot analysis using antibodies specific to the tyrosine phosphorylated GSK-3. Using this antibody, we also showed that GSK-3 tyrosine phosphorylation was high in motile compared to immotile sperm. Immunocytochemistry revealed that GSK-3 is present in the flagellum and the anterior portion of the sperm head. These data suggest that GSK-3, regulated by phosphorylation, could be a key element underlying motility initiation in the epididymis and regulation of mature sperm function.

Isolation and molecular characterization of AKAP110, a novel, sperm-specific protein kinase A-anchoring protein

Agents that increase intracellular cAMP are potent stimulators of sperm motility. Anchoring inhibitor peptides, designed to disrupt the interaction of the cAMP-dependent protein kinase A (PKA) with A kinase-anchoring proteins (AKAPs), are potent inhibitors of sperm motility. These data suggest that PKA anchoring is a key biochemical mechanism controlling motility. We now report the isolation, identification, cloning, and characterization of AKAP110, the predominant AKAP detected in sperm lysates. AKAP110 cDNA was isolated and sequenced from mouse, bovine, and human testis libraries. Using truncated mutants, the RII-binding domain was identified. Alignment of the RII-binding domain on AKAP110 to those from other AKAPs reveals that AKAPs contain eight functionally conserved positions within an amphipathic helix structure that are responsible for RII interaction. Northern analysis of eight different tissues detected AKAP110 only in the testis, and in situ hybridization analysis detected AKAP110 only in round spermatids, suggesting that AKAP110 is a protein found only in male germ cells. Sperm cells contain both RI, located primarily in the acrosomal region of the head, and RII, located exclusively in the tail, regulatory subunits of PKA. Immunocytochemical analysis detected AKAP110 in the acrosomal region of the sperm head and along the entire length of the principal piece. These data suggest that AKAP110 shares compartments with both RI and RII isoforms of PKA and may function as a regulator of both motility- and head-associated functions such as capacitation and the acrosome reaction.

Self-injurious behavior is decreased by cyproterone acetate in adult male rhesus (Macaca mulatta)

Self-injurious behavior (SIB) presents a serious problem in laboratory macaques that cannot be socially housed for scientific reasons and among institutionalized children and adults where it is often associated with different forms of brain dysfunction. We have experienced limited success in reducing SIB in macaques by enhancing their environment with enrichment devices. Psychotropic drugs also help, but problems are associated with their use. Because sexual and aggressive behavioral problems in men have been treated with progestational drugs, we tested the efficacy of cyproterone acetate (CA, 5-10 mg/kg/week) on reducing SIB in 8 singly housed, adult male rhesus macaques. The main findings were: (1) SIB and other atypical behaviors were significantly reduced during CA treatment; (2) serum testosterone was significantly reduced during CA treatment; (3) cerebral spinal fluid (CSF) levels of 5HIAA and HVA, metabolites of serotonin and dopamine, respectively, declined significantly during CA treatment; (4) the duration of SIB positively correlated with levels of 5HIAA in CSF; but (5) sperm counts were not reduced during treatment. Thus, CA was a partially effective treatment (3 months) for adult male macaques whose behavioral problems include SIB. In summary, CA reduced SIB, overall aggression, serum testosterone, CSF 5HIAA, and CSF HVA. We hypothesized that the progestin activity of CA represses the hypothalamic gonadal axis and decreases testosterone, which in turn decreases SIB. In addition, we speculate that the decrease in 5HIAA and HVA in CSF may have been caused by progestins decreasing the activity of MAO. Therefore, the reduction of SIB may also be related to an increase in the availability of active monoamines in the CNS.

Motility potential of macaque epididymal sperm: the role of protein phosphatase and glycogen synthase kinase-3 activities

Human and monkey ejaculated sperm contain protein phosphatase-1 (PP1), PP1 inhibitor 2 (12), and glycogen synthase kinase-3 (GSK-3). Inhibition of ejaculated human sperm protein phosphatase (PP) activity with calyculin-a (CL-A) significantly stimulates motility, implicating protein dephosphorylation in motility regulation. The present experiments were conducted to characterize and compare PP and GSK-3 activity in monkey caput and caudal epididymal sperm, to determine the cellular distribution of these enzymes, and to test the thesis that epididymal sperm PP activity is inversely related to motility. Caput epididymal sperm populations, (8.8% motile) contained levels of PP activity that were >3 times as high as those of caudal spermatozoa. This PP activity was further identified by inhibitor response profiles as PP1. In both caput and caudal sperm, the majority of this PP1 activity was localized in 100,000 x g soluble fractions. Western blot analysis indicated that a portion of this difference was the result of elevated amounts of PP1 in caput compared with caudal epididymal sperm. The presence of GSK-3 activity was undetectable in 100,000 x g insoluble fractions of epididymal sperm, whereas both caput and caudal sperm soluble fractions contained GSK-3 activity, which was approximately threefold higher in caput sperm compared with caudal populations. Treatment of caput epididymal sperm from the rhesus macaque with the PP inhibitor CL-A resulted in a significant, dose-dependent increase from 8 to 38% motile cells (without any effect on their path velocity). In contrast, CL-A had no significant influence on either percent motility or path velocity of caudal epididymal sperm. Cytosolic PP1 and GSK-3 activities appear to be inversely related to the motility of monkey epididymal sperm and may have a regulatory role in the development of the potential for motility in epididymal sperm.

Effect of acute exposure of the organophosphate insecticide Rogor on some biochemical aspects of Clarias batrachus (Linnaeus)

Indian catfish (Clarias batrachus), a common fish of commercial importance, was exposed to a sublethal concentration (1/3 of 96 h LC50 value) of Rogor for periods ranging from 24 to 192 h. The changes in glycogen, lactate, lactate dehydrogenase, and glycogen phosphorylase (a, ab) contents of muscle tissue were studied. A gradual decrease in muscle glycogen and an increase in lactate contents were observed. The activity level of lactate dehydrogenase showed a sharp rise initially for 48 h followed by a decline after 96 and 192 h. The glycogen phosphorylase a and ab in muscle tissue enhanced in response to Rogor exposure.

Nicotinic receptor-induced apoptotic cell death of hippocampal progenitor cells

Nicotine has many effects on CNS functions, presumably through its action on neuronal nicotinic acetylcholine receptors (AChRs). One subclass of AChRs that binds the snake venom toxin alpha-bungarotoxin (alpha-Bgt-AChRs) has been shown to modulate neurotransmission in the brain. We now show that alpha-Bgt-AChR activation by low doses of nicotine results in apoptotic cell death of both primary and immortalized hippocampal progenitor cells. In HC2S2-immortalized hippocampal progenitors, nicotine is cytotoxic to undifferentiated cells, whereas it spares the same cells once differentiation has been induced. The activation of alpha-Bgt-AChRs by nicotine results in the induction of the tumor suppressor protein p53 and the cdk inhibitor p21. The cytotoxic effect of nicotine is dependent on extracellular calcium levels and is probably attributable to the poor ability of undifferentiated progenitors to buffer calcium loads. The major calcium buffer in these cells, calbindin D28K, is present only after differentiation has been induced. Furthermore transfection of undifferentiated cells with calbindin results in dramatic protection against the cytotoxic effects of nicotine. These results show that nicotine abuse could have significant effects on the survival of progenitor populations in the developing and adult brain and also suggest an endogenous role for alpha-Bgt-AChRs in neuronal development and differentiation.

Subcellular localization of the regulatory subunits of cyclic adenosine 3',5'-monophosphate-dependent protein kinase in bovine spermatozoa

Cyclic AMP (cAMP) is a regulator of sperm flagellar activity. The action of this cyclic nucleotide is presumably mediated by cAMP-dependent protein kinase (PKA). PKA is localized or targeted to specific subcellular sites through the interaction of PKA regulatory subunits with A-kinase anchoring proteins (AKAPs). We have recently shown that the addition of PKA anchoring inhibitor peptides to spermatozoa leads to the complete arrest of motility. A knowledge of the subcellular localization of PKA and AKAPs is essential for an understanding of how cAMP acts in spermatozoa. In this report, monospecific, affinity-purified, antipeptide antibodies were used to determine the distribution of the regulatory (R) subunit isoforms. Immunocytochemistry staining revealed that RIalpha and RIbeta subunits are both localized predominantly in the acrosomal segment of the head, although they have distinct staining patterns within this region. In addition to the head, RIbeta was observed in the midpiece of the tail while RIalpha was detected in the connecting piece. RIIalpha is prominent in the axonemal region of the flagellum but was not observed in the head region. These data suggest distinct roles for each of these isoforms in sperm functions such as motility and the acrosome reaction.

A tyrosine-phosphorylated 55-kilodalton motility-associated bovine sperm protein is regulated by cyclic adenosine 3',5'-monophosphates and calcium

Sperm motility is regulated by protein phosphorylation. We have recently shown that a serine/threonine phosphatase system is involved in motility regulation. Two of the components of the phosphatase system, GSK-3 and PP1gamma2, are regulated by tyrosine phosphorylation. During our investigation of sperm tyrosine-phosphorylated proteins we discovered a 55-kDa protein whose tyrosine phosphorylation correlates closely to the motility state of sperm. This protein is tyrosine phosphorylated to a much higher degree in motile caudal than in immotile caput epididymal sperm. Motility inhibition of caudal epididymal sperm by protein kinase A (PKA) anchoring inhibition or by ionomycin-induced calcium overload led to the virtual disappearance of tyrosine phosphorylation of the 55-kDa protein. Conversely, treatment of sperm with motility activators, isobutylmethylxanthine or 8-bromo-cAMP, resulted in increased tyrosine phosphorylation of the protein. The protein was present in the soluble 100 000 x g supernatants of sperm extracts and was heat labile. Chromatography through diethylaminoethyl-cellulose and Western blot analysis showed that this 55-kDa protein is not a regulatory subunit of PKA or alpha-tubulin. Our results represent the identification of a soluble protein whose tyrosine phosphorylation varies directly with motility and suggest that motility regulation may involve cross talk between PKA, calcium, and tyrosine kinase pathways.

Protein kinase A-anchoring inhibitor peptides arrest mammalian sperm motility

Cyclic AMP-dependent protein kinase (PKA) is anchored at specific subcellular sites through the interaction of the regulatory subunit (R) with protein kinase A-anchoring proteins (AKAPs) via an amphipathic helix binding motif. Synthetic peptides containing this amphipathic helix domain competitively disrupt PKA binding to AKAPs and cause a loss of PKA modulation of cellular responses. In this report we use S-Ht31, a cell-permeant anchoring inhibitor peptide, to study the role of PKA anchoring in sperm. Our analysis of three species of mammalian sperm detected three isoforms of PKA (RIIalpha, RIIbeta, and RIbeta) and one 110-kDa AKAP. The addition of S-Ht31 to bovine caudal epididymal sperm inhibits motility in a time- and concentration-dependent manner. A control peptide, S-Ht31-P, identical to S-Ht31 except for a proline for isoleucine substitution to prevent amphipathic helix formation, had no effect on motility. The inhibition of motility by S-Ht31 is reversible but only if calcium is present in the suspension buffer, suggesting a role for PKA anchoring in regulating cellular calcium homeostasis. Surprisingly, inhibition of PKA catalytic activity had little effect on basal motility or motility stimulated by agents previously thought to work via PKA activation. These data suggest that the interaction of the regulatory subunit of PKA with sperm AKAPs, independent of PKA catalytic activity, is a key regulator of sperm motility and that disruption of this interaction using cell-permeable anchoring inhibitor peptides may form the basis of a sperm-targeted contraceptive.

Elevation of intracellular calcium levels in neurons by nicotinic acetylcholine receptors

The recognition that intracellular free calcium serves as a ubiquitous intracellular signal has motivated efforts to elucidate mechanisms by which cells regulate calcium influx. One route of entry that may offer both spatial and temporal fine resolution for altering calcium levels is that provided by cation-permeable, ligand-gated ion channels. Biophysical measurements as well as calcium imaging techniques demonstrate that neuronal nicotinic acetylcholine receptors as a class have a high relative permeability to calcium; some subtypes equal or exceed all other known receptors in this respect. Activation of nicotinic receptors on neurons can produce substantial increases in intracellular calcium levels by direct passage of calcium through the receptor channel. When multiple classes of nicotinic receptors are expressed by the same neuron, each appears capable of increasing calcium in the cell but may differ with respect to location, temporal response, agonist sensitivity, or regulation in achieving it. As a result, nicotinic receptors must be considered strong candidates for signaling molecules through which neurons regulate a diverse array of cellular events.

Sperm motility development in the epididymis is associated with decreased glycogen synthase kinase-3 and protein phosphatase 1 activity

Immotile bovine caput epididymal sperm contain levels of protein phosphatase activity twofold higher than do mature motile caudal sperm. Comparison of the inhibition profiles of endogenous phosphatase activities detected by okadaic acid (OA) and calyculin A (CA) revealed a pattern consistent with the predominance of a type 1 protein phosphatase (PP1). Immunoblot analysis identified PP1 gamma 2 (the testis-specific isoform of PP1) as the only PP1 isoform in sperm and showed little protein phosphatase 2A (PP2A). In addition, of the known PP1 inhibitors, i.e., DARPP-32, inhibitor 1 (I1), and inhibitor 2 (I2), only I2-like activity was detected in sperm. Inhibition of PP1 by the heat-stable I2-like activity purified from sperm could be reversed with purified glycogen synthase kinase-3 (GSK-3). Furthermore, sperm extracts contain an inactive complex of PP1 and I2 (termed PP1I) that could also be activated by purified GSK-3. The presence of GSK-3 in sperm was demonstrated by activation of purified PP1I, and quantitation revealed that immotile caput sperm contained sixfold higher GSK-3 activity than motile caudal sperm. Immunoblot analysis confirmed the expression of GSK-3 in sperm and revealed the occurrence of both the alpha and beta isoforms. Our findings suggest that the higher PP1 activity measured in immotile sperm, presumably due to higher GSK-3 activity, is responsible for holding motility in check. This conclusion was supported by the observation that the phosphatase inhibitors OA and CA, at micromolar and nanomolar levels, respectively, were able to induce motility in completely immotile bovine caput epididymal sperm and to stimulate the kinetic activity of mature caudal sperm. The intrasperm levels of cAMP, pH, and calcium were unaltered by treatment with these inhibitors. The results suggest a biochemical basis for the development and regulation of sperm motility and a possible physiological role for the PP1/I2/GSK-3 system.

Primate sperm contain protein phosphatase 1, a biochemical mediator of motility

Sperm motility initiation, capacitation, and hyperactivation are modulated by an interplay of intracellular Ca2+, cAMP, and pH. Mechanisms by which these mediators alter sperm function have not been elucidated but may involve reversible alterations in regulatory protein phosphorylation. Studies were designed 1) to investigate the influence of the protein phosphatase (PP) inhibitor calyculin A (CA) on human sperm motility and 2) to characterize the CA-sensitive PP and its endogenous regulators in human and rhesus monkey sperm. CA (50 nM) treatment of human sperm resulted in an increase in percentage motility and an acceleration in mean path velocity. Inhibition of either protein phosphatase-1 (PP1) or protein phosphatase-2A (PP2A) could be responsible for this motility stimulation, since both of these phosphatases are sensitive to nanomolar quantities of CA. PP activity in human (n = 4) and rhesus monkey (n = 4) sperm sonicates was measured using [32P]-phosphorylase-a, the preferred substrate for PP1 and PP2A, in the absence of divalent cations. Human (6.2 +/- 4.5 x 10(-2) mU/10(6) sperm) and monkey (4.3 +/- 0.8 x 10(-2) mU/10(6) sperm) sonicates contained activity tentatively identified as PP1 on the basis of inhibition profiles in okadaic acid (OA) and CA. Western blot analysis with antibodies against various isoforms of PP1 subsequently documented the presence of PP1 gamma 2 in human and monkey sperm. PP1 activity in most tissues is regulated by the heat-stable inhibitors I1 or I2. Sperm sonicates contained inhibitor activity similar to I2 as well as glycogen synthase kinase-3 (GSK-3) activity, which is involved in the activation of the PP1-I2 complex. These results indicate, for the first time, that human and rhesus monkey sperm contain PP1 and regulators of PP1 and that inhibition of PP1 activity by CA can enhance motility.

Post-translational regulation of neuronal acetylcholine receptors stably expressed in a mouse fibroblast cell line

Second messenger regulation of neuronal acetylcholine receptors (AChRs) was investigated in a mouse fibroblast cell line, M10, stably transfected with chicken alpha 4 and beta 2 cDNAs. Both forskolin and 8-bromo-cyclic adenosine 3',5'-monophosphate (cAMP) induced large increases in the numbers of AChRs. The increases were due in part to increased transcription and translation of the alpha 4 and beta 2 genes. Blockade of protein synthesis with cycloheximide, however, revealed that forskolin also exerts a post-translational effect, increasing the number of surface receptors by twofold. Immunoblot analysis of sucrose gradient fractions confirmed that the cells had a large fraction of unassembled subunits potentially available for receptor assembly. The post-translational effect of forskolin was blocked by H-89, an inhibitor of cAMP-dependent protein kinase, and by okadaic acid, an inhibitor of phosphatases 1 and 2A. Nicotine also acted post-translationally to induce a twofold increase in the number of surface receptors, but the mechanism differed from that utilized by forskolin, since the effects of the two agents were additive and were differentially affected by okadaic acid. The results suggest that protein phosphorylation-dephosphorylation mechanisms act post-translationally to increase the number of neuronal AChRs maintained on the cell surface. This could be achieved by increasing the efficiency of receptor assembly, transport, or stabilization on the cell surface.

Acetylcholine differentially affects intracellular calcium via nicotinic and muscarinic receptors on the same population of neurons

Multiple receptor subtypes activated by the same ligand but coupled to different second messengers can produce divergent signaling in a cell, while receptors activated by different ligands but sharing the same second messenger can produce convergent signaling. We show here that chick ciliary ganglion neurons have three classes of receptors activated by the same neurotransmitter, acetylcholine, and that all three regulate the same second messenger, intracellular free calcium. Activation of muscarinic receptors on the neurons stimulates phosphatidylinositol turnover and induces calcium oscillations that are initiated and maintained by calcium release from caffeine/ryanodine-insensitive intracellular stores. Extracellular calcium is required to sustain the oscillations, while cadmium abolishes them. Activation of either of two classes of nicotinic receptors, distinguished both by location on the neurons and by subunit composition, induces a single, rapid elevation in intracellular calcium without inducing phosphatidylinositol turnover. The nicotinic responses are entirely dependent on extracellular calcium, show no dependence on release from internal stores, and do not display oscillations. Low concentrations of the native agonist, acetylcholine, induce repetitive calcium spikes in the neurons characteristic of muscarinic receptors, while higher concentrations induce nonoscillating increases in intracellular calcium that include contributions from nicotinic receptors. The three classes of receptors also differ in the acetylcholine concentration required to elicit a response. These differences, together with differences in receptor location and sources of calcium mobilized, may enable the receptor subtypes to target different sets of calcium-dependent processes for regulation.

Arachidonic acid as a possible negative feedback inhibitor of nicotinic acetylcholine receptors on neurons

Neuronal acetylcholine receptors, being highly permeable to calcium, are likely to regulate calcium-dependent events in neurons. Arachidonic acid is a membrane-permeant second messenger that can be released from membrane phospholipids by phospholipases in a calcium-dependent manner. We show here that activation of neuronal acetylcholine receptors triggers release of 3H-arachidonic acid in a calcium-dependent manner from neurons preloaded with the fatty acid. Moreover, low concentrations of arachidonic acid reversibly inhibit the receptors and act most efficiently on receptors likely to have the highest permeability to calcium, namely receptors containing alpha 7 subunits. Low concentrations of arachidonic acid also reversibly inhibit alpha 7-containing receptors expressed in Xenopus oocytes following injection of alpha 7 cRNA. The oocyte results indicate following injection of alpha 7 cRNA. The oocyte results indicate that the inhibition is a feature of the receptors rather than a consequence of neuron-specific machinery. The inhibition is not mediated by specific metabolites of arachidonic acid because the effects can be mimicked by other fatty acids; their effectiveness correlates with their content of double bonds. In contrast to arachidonic effects on calcium currents, inhibition of neuronal nicotinic receptors by the fatty acid cannot be prevented by blocking production of free radicals or by inhibiting protein kinase C. An alternative mechanism is that arachidonic acid binds directly to the receptors or perturbs the local environment in such a manner as to constrain receptor function.(ABSTRACT TRUNCATED AT 250 WORDS)

Carbohydrate metabolism in hepatic tissue of freshwater catfish Clarias batrachus L. during dimethoate exposure

Clarias batrachus L., a freshwater catfish of commercial importance, was exposed to a sublethal concentration of dimethoate (Rogor). The acute effect of dimethoate on some aspects of carbohydrate metabolism of hepatic tissue was studied after 1, 2, 4 and 8 days. The glycogen content was depleted, whereas the lactate level was elevated throughout the experimental period and an increase in lactate dehydrogenase was observed. The activity levels of glycogen phosphorylase a and ab in the hepatic tissue were increased during dimethoate stress. The results suggest that carbohydrate metabolism was adversely affected in the hepatic tissue by the organophosphate insecticide dimethoate.

Science for art's sake

Hollywood's absent-minded professor, always a cliché, is now more unrealistic than ever before. Just how can biological research move forward in the modern era?

Apolipoprotein-D polymorphism: a genetic marker for obesity and hyperinsulinemia

Obesity frequently clusters with hypertension, hyperlipidemia, non-insulin-dependent diabetes mellitus, and ischemic heart disease with hyperinsulinemia as syndrome X. Although central obesity has been recognized to have a strong genetic component, few candidate genes have been studied in this disorder. After a recently described association between the apolipoprotein-D (Apo-D) gene polymorphism and non-insulin-dependent diabetes mellitus by our group, we have now looked at a TaqI polymorphism of the Apo-D gene in two other components of syndrome X, namely obesity and hyperinsulinemia. Apo-D genotype differences were found between obese subjects (n = 57) and slim controls (n = 57; P = 0.006). Furthermore, in the obese group an association was found between the Apo-D genotype and fasting insulin (P < 0.001). Preliminary evidence, therefore, suggests that the TaqI Apo-D polymorphism can be used as a genetic marker for obesity and several components of syndrome X.

Evidence against a functional ATP-dependent calcium extrusion mechanism in bovine epididymal sperm

Bovine epididymal sperm resuspended in ionic buffers take up relatively large amounts of calcium. This uptake, which is almost entirely mitochondrial, apparently bypasses the sperm cytosol. The direct mitochondrial loading is an unusual aspect of sperm calcium uptake, which suggests that the plasma membrane region surrounding the mitochondria should be highly permeable to calcium, whereas the membrane domains surrounding the head and tail regions of sperm should be impermeable. This study was undertaken to determine the role of a plasma membrane calcium ATPase in sperm calcium homeostasis. Kinetics of calcium (45Ca2+) uptake into intact and permeabilized caudal epididymal sperm confirmed that mitochondrial calcium uptake occurs with virtually no resistance from the surrounding plasma membrane. Cytoplasmic calcium accumulation by sperm depleted of intracellular ATP, measured in the presence of mitochondrial calcium uptake inhibitors, showed no increase upon energy depletion as would be expected if an ATP-dependent calcium extrusion mechanism were present. Furthermore, lowering the incubation temperature to further reduce the activity of the calcium ATPase in these energy-depleted sperm was also without effect on calcium accumulation. The calcium ATPase inhibitor vanadate, even at high concentrations, failed to increase intracellular 45Ca2+ accumulation. However, vanadate was effective in inhibiting motility showing that the compound was accumulated into sperm to inhibit flagellar dyenin ATPase. Therefore, the lack of effect of vanadate on 45Ca2+ accumulation was not due to its inability to enter sperm. Other calcium ATPase inhibitors such as quercetin, thapsigargin, and cyclopiazonic acid, which readily demonstrate ATP-dependent calcium extrusion in other somatic cells, were also without effect on sperm calcium accumulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Neuronal acetylcholine receptors that bind alpha-bungarotoxin with high affinity function as ligand-gated ion channels

Neuronal membrane components that bind alpha-bungarotoxin with high affinity can increase intracellular levels of free calcium, demonstrating the components function as nicotinic receptors. Though such receptors often contain the alpha 7 gene product, which by itself can produce ionotropic receptors in Xenopus oocytes, numerous attempts have failed to demonstrate an ion channel function for the native receptors on neurons. Using rapid application of agonist, we show here that the native receptors are ligand-gated ion channels which are cation selective, prefer nicotine over acetylcholine, and rapidly desensitize. Much of the calcium increase caused in neurons by the receptors under physiological conditions appears to result from their depolarizing the membrane sufficiently to trigger calcium influx through voltage-gated channels.

Does the rapid response to cisplatin-based chemotherapy justify its use as primary treatment for intracranial germ-cell tumours?

We reviewed presentation, diagnostic problems and outcome of eight cases of primary intracranial germ-cell tumour (4 germinoma, 4 teratoma) treated with Cisplatin-based chemotherapy at our centre over the last ten years. Three patients received primary chemotherapy with Cisplatin-based regimens followed by radiotherapy for subsequent relapse, two were treated with a combination of chemotherapy and external radiotherapy, and three received chemotherapy for relapse after radiotherapy. The response to Cisplatin-based chemotherapy was rapid, with some patents exhibiting symptomatic improvement within 24 h. Four patients achieved complete remission within 21 days, and three of these have remained progression-free. Four patients in total have survived for 32 to 128+ months. Six of seven patients tested pre-treatment had central diabetes insipidus and five had partial anterior pituitary failure. The endocrine deficit progressed in two, with no recovery in any patient. It is arguable that chemotherapy should be the primary therapy in all such cases diagnosed on the basis of tumour markers and imaging, with surgery and/or radiotherapy as later options. As these tumours are rare, such questions can only be answered by collaboration studies.

Serotonin modulates nicotinic responses of adrenal chromaffin cells

5-Hydroxytryptamine (5-HT) specifically and reversibly inhibits nicotine-induced currents and catecholamine release in bovine adrenal chromaffin cells in culture. Pharmacological analysis indicates that the inhibition is not mediated by known 5-HT receptor subtypes. The inhibition is noncompetitive over a range of nicotine concentrations between 1 and 100 microM. Preincubation with either 5-HT or substance P significantly protects the response from nicotine-induced desensitization. It is concluded that 5-HT inhibits nicotinic acetylcholine receptors on bovine adrenal chromaffin cells, probably by binding to a noncompetitive site on the receptor itself. Because both blood and the chromaffin cells contain 5-HT, the inhibition provides an opportunity for negative control of catecholamine secretion from the adrenals.